This Section aims to understand the principles and mechanisms that govern intracellular calcium signals in glial cells and neurons. While glial cells lack electrically excitable properties similar to neurons, they do, however, possess a form of calcium based excitability whereby intracellular calcium signals propagated as waves serve as long distance signals following activation by neurotransmitters. The research focus of the Section includes studies on the signal transduction mechanisms of various receptor systems in glial cells as well as the cell biology of calcium signalling in both glia and neurons. One objective is to understand processes that support temporal and spatial signalling within cells and between cells at the molecular level. A second objective is to understand the precise nature of glial cell signals resulting from neuronal activity. Finally, this Section aims to describe in detail the ionic basis for cellular excitability in pineal cells.